The present disclosure relates generally to equipment utilized and operations performed in conjunction with a subterranean well and, in an embodiment described herein, more particularly provides phase-controlled well flow control.
Many reservoirs containing valuable quantities of hydrocarbons have been discovered in subterranean formations from which recovery of the hydrocarbons has been very difficult due to a relatively high viscosity of the hydrocarbons and/or the presence of viscous tar sands in the formations. In particular, when a production well is drilled into a subterranean formation to recover oil residing therein, often little or no oil flows into the production well even if a natural or artificially induced pressure differential exits between the formation and the well. To overcome this problem, various thermal recovery techniques have been used to decrease the viscosity of the oil and/or the tar sands, thereby making the recovery of the oil easier.
One such thermal recovery technique utilizes steam to thermally stimulate viscous hydrocarbon production by injecting steam into a wellbore to heat an adjacent subterranean formation. However, the steam typically is not evenly distributed throughout the wellbore, resulting in a temperature gradient along the wellbore. As such, areas that are hotter and colder than other areas of the wellbore (i.e., hot spots and cold spots) undesirably form in the wellbore.
The cold spots lead to the formation of pockets of hydrocarbons that remain immobile. Further, the hot spots allow the steam to break through the formation and pass directly to a production wellbore, creating a path of least resistance for the flow of steam to the production wellbore. Consequently, the steam bypasses a large portion of the hydrocarbons residing in the formation, thus failing to heat and mobilize the hydrocarbons, and flow of the steam into the production wellbore can lead to damage to the surrounding formation, production of formation fines, etc.
Therefore, it may be seen that improvements are needed in the art of flow control in wells. These improvements may be usable in applications other than the thermal recovery techniques discussed above.